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2. Brake diagnostic equipment

5th April 1968, Page 78
5th April 1968
Page 78
Page 81
Page 78, 5th April 1968 — 2. Brake diagnostic equipment
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Which of the following most accurately describes the problem?

by R. D. Cater

OF THE COMPANIES producing brake servicing equipment, only JAR. Garage Equipment, of Birmingham, has specialized in the development of gear aimed at reducing labour costs by eliminating faulty diagnosis. Labour is the most expensive item of workshop outlay and quite often used badly because too much time is taken up tracing the cause of a braking fault. Expense incurred in this way can be further multiplied by hit-and-miss methods of curing what someone imagines the trouble to be. Frequently one hears a fitter say: "We changed everything and eventually cured it, but we still do not know what the trouble really was." And here is just where JAR comes into the picture.

Referring first of all to the smaller types of vehicle with hydraulic braking systems, some users make the mistake of presuming there is not a lot to go wrong with this simple type of system. One seldom sees or hears of the hydraulic system itself receiving any attention, that is until a failure occurs. Failure, however, can be the cause of a fatality or serious injury and to be fair to all concerned, operators should look into the hydraulics in just the same manner that they investigate other parts of braking systems. The JARC 50 range, is designed for a complete investigation and servicing of hydraulic brakes. It comprises a tank to hold hydraulic fluid, around which there is a second chamber, capable of withstanding in excess of 60 p.s.i. of air pressure. The inner tank is coupled to the outer tank via a pipe and pressure-reducing valve, through which a balanced pressure of 20 p.s.i. is maintained.

Probably the most important feature about the JARC equipment is that all existing known couplings and unions are supplied with the kit. Why important? Because it is in searching around for the appropriate fitting that many expensive man-hours can be lost. With the correct fitting in place and the JARC coupled up the fitter can carry out ti following operations single-handed: he can completely empty ti system by directing air from the pressure chamber into the system: pressure test on the system after repairs are carried out will tell hi whether the system is leak proof, before the fluid is added. He ca check numerous defects that would otherwise be traceable only t stripping, and not always then. The master-cylinder valve can also t checked under pressure.

With these points cleared it remains to fill the system with fref. fluid and bleed. Both these operations are carried out at the turn of valve by one man working on his own. Systems can be bled withoi resorting to pumping the brake pedal and, under a controlled ar constant pressure, quickly dispel any trapped air.

Other—perhaps not so noticeable—advantages to be gained fro this unit are complete elimination in wastage of-fluid, and of tt chances of dust and grit being introduced to systems by the use , open-topped cans.

There are three hydraulic-brake servicing units in this range, tt Standard, which has a fluid capacity of 1.25gal• and costs £65, tt Fleetserver which is similar in design but has a fluid capacity , 2.5gal and costs £84, and the Junior which holds only 1gal of flui does not embody an air reservoir, and costs £40 10s. This last mod must be connected to an air supply while in LIM

One other piece of equipment goes with any of those mention( above to make up a complete, straightforward hydraulic test ar servicing unit and that is the JARC 50 HP tester. This unit costs El 7s 6d and comprises an accurate gauge which reads up to 2,0C

a flexible connection and a full set of adaptors. It will check line pressures, reveal weak or creeping wheel cylinders and test the efficiency of pressure regulating valves.

For systems having servo assistance, the JAR C Servac tester —which includes the HP Tester—completes all the functions necessary to diagnose every known fault in Servo hydraulic systems. By connecting the gauge into the line between the exhauster and the non-return valve it is possible to check both the efficiency of the exhauster with regard to its ability to build a vacuum, and the non-return valve regarding its capability of holding it once made. This test also checks the soundness of the reservoir and the accuracy of the dash-board gauge at the same time.

Detailed instructions are included with all these devices showing how the various tests should be carried out. Also included with the Servac tester are charts showing comparative performances of wide ranges of servo units. This enables one to check if a particular unit is up to scratch.

For investigation into air pressure systems the JARC 50 Air Brake Tester is again capable of diagnosing all known faults. As with the other sets, it is the provision of a complete set of fittings which permits the fitter to couple into almost any critical part of the system to carry out an investigation of components such as brake valves, unloader valves, reaction valves and relief valves, without the need to dismantle them. It will also check the soundness of pipelines, brake chambers and reservoirs as well as determining the effectiveness of the compressor and the accuracy of panel gauges.

All these points are of importance when a vehicle's brakes are below par, and to be able to check them in double-quick time with complete accuracy is a great step towards knowing how the next step in the operation should be tackled.

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Locations: Birmingham

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